Effect of temperature and substrate on PEF inactivation of Lactobacillus plantarum in an orange juice-milk beverage

The inactivation kinetics of Lactobacillus plantarum in an orange juice-milk beverage treated by Pulsed Electric Fields (PEF) were studied. Experimental data were fitted to Bigelow and Hulsheger kinetic models and Weibull frequency distribution function. Results indicate that both Hulsheger model and Weibull function fit well the experimental data being Accuracy factor values (Af) closer to I and Mean Square Error (MSE) closer to 0. The tcw parameter of the Weibull model can be considered as a kinetic indicator as it expresses the microorganism's resistance to treatment by electric pulses. An increase in temperature favoured the inactivation of L. plantarum by PEF as reflected by a decreased in tcw value. Under the same conditions to those studied by other authors we reached less inactivation of L. plantarum in the beverage used in this study than in substrates with a simpler composition.